Assoc. Prof. Dr. Dragi Dojcinovski, grad. civil eng., Head of Section,
e-mail: dragi@pluto.iziis.ukim.edu.mk,
Senior Scientific Collaborator Dr.Gavril Mirakovski, grad. geophysicist,
e-mail: mirak@pluto.iziis.ukim.edu.mk,
Senior Scientific Collaborator Dr.Dusan Aleksovski, grad. Geophysicist,
e-mail: dalek@pluto.iziis.ukim.edu.mk,
Scientific Collaborator Dr. Biserka Dimiskovska, grad. civil eng,
e-mail: biserka@pluto.iziis.ukim.edu.mk,
Senior Research Assistant Tatjana Olumceva, MSc, grad. physicist,
e-mail: olumceva@pluto.iziis.ukim.edu.mk,
Irena Gjorgjieska, graduated physicist/geophysicist,
e-mail: gj_irena@pluto.iziis.ukim.edu.mk,
Vladimir Koviloski, mechanical engineer,
e-mail: vladimir@pluto.iziis.ukim.edu.mk
Jovanovski Gjorgji, accomplished vocational school,
e-mail: gjoko@pluto.iziis.ukim.edu.mk,
Dimitar Blazeski, accomplished vocational school,
e-mail: dime@pluto.iziis.ukim.edu.mk
Strong Motion Laboratory
In order to provide permanent maintenance of the installed network and processing of the obtained strong motion records, the IZIIS Strong Motion Laboratory was established and it is presently part of the Department for Natural and Technological Hazards and Ecology.
Responsibilities:
- Maintenance of the Macedonian Strong Motion Network (SMN);
- Collection, processing, acquisition and archiving of recorded strong motion data;
- Maintenance of instruments installed on special and capital investment facilities in neighbouring countries /Slovenia: Dams Moste, Zlatolicje, Fala and Doblar, NPP Krsko; Montenegro: Dam Piva; BIH: Dams: Gorica-I and Grancarevo, etc.
The instruments are located in all the regions of Macedonia characterized by pronounced seismic activity and are installed on various types of structures – dams, bridges, tall buildings, industrial plants, administrative and educational buildings providing continuous monitoring of the seismic activity.
In almost 40 years of operation, SMN recorded earthquakes with magnitudes 3<M<7.2 resulting in a database with more than 1200 strong motion records obtained from near and distant seismic sources on different soil conditions (bedrock and soil deposit), and different types of structures. These data have been applied in engineering practice for:
- definition and improvement of the Codes for design and construction in seismic prone areas;
seismic hazard analyses;
- definition of the seismic parameters for particular sites;
- repair, strengthening and retrofitting of existing structures (after being exposed to strong earthquakes).
Since 1973, several strong earthquakes have occurred on the territory of former Yugoslavia, (the Montenegro coastal area - 1979, M= 7.0; Kopaonik - 1980, M= 6.3; Banja Luka-1981, M= 5.4, Negotino 1985, M= 5.1, Bitola 1994, M= 5.2, Valandovo 2009, M=5.2) and the neighboring countries (Friuli, Italy-1976, M= 6.5; Vranchea, Romania-1977, M=7.2, Thessaloniki, Greece-1978, M=6.3, Griva, Greece-1990, M=5.7, etc.). Many earthquakes of moderate intensity (M>3.5) have occurred, too. Accelerogrammes have been obtained by instruments located at different locations, i.e., not only on locations in the immediate vicinity of the epicentral areas but also on locations at a distance of L ³ 150 km.
The databank contains over 1200 accelerogrammes out of which 823 have been obtained on instruments installed at free field and 383 on instruments installed on different engineering structures (high rises, dams, bridges and power plants). For the preceding years, the recorded accelerogrammes have widely been applied in the everyday engineering practice of seismic design of different kinds of structures, seismic hazard analyses and in the process of defining technical regulations for seismic design.
Macedonian Strong Motion Network
The strong motion network of former Yugoslavia was developed by the Institute during the seventies of the 20th century. The Macedonian strong motion network was an integral part of the former Yugoslav strong motion network that was maintained by the Institute until the early nineties of the last century.
The strong motion network installed in 1972 in the territory of Macedonia consists of 125 accelerographs type SMA-1, K-2 with episensors, GNC-CR12 with accelerometers type SSA-320 and quake data recorder QDR .
Presently, the Macedonian strong motion network (Fig.1) consists of 125 SMA-instruments installed in bed rock/free-field locations and various structures like buildings, bridges, dams, etc. Table 1 shows the distribution of the installed instruments, while Table 2 provides information on types of instrumented structures.
The strong-motion instrument network includes 125 accelerographs and 54 seismoscopes. In addition, the network also includes instruments installed by IZIIS for the needs of other projects and financed by other investors. These instruments are mainly installed at characteristic structures and locations foreseen for structures of capital importance.
Table 1. Distribution of instruments
Location |
Accelerographs |
On bed rock |
9 |
On characteristic soil |
16 |
On structure |
100 |
Total |
125 |
Table 2. Instrumented structures
Structures |
Number of instruments |
Buildings |
32 |
Dams |
48 |
Bridges |
20 |
Total |
100 |
The 3D strong motion recording network in Ohrid was founded in 1976 within the joint US-YU project “Experimental and Theoretical Investigations for Definition of Methods for Seismic Microzonation on the Basis of Weak and Strong Earthquakes”. The aim was to install a local 3D network of three component accelerographs for recording weak and strong earthquake motions, ambient and forced vibrations in order to provide information for experimental and theoretical investigations of the fundamental problems in engineering seismology and earthquake engineering related to the influence of the seismic motion propagation characteristics, local soil, foundation-soil interaction and seismic response of structures.
The Debar-Ohrid region was chosen because of its pronounced seismic activity that can generate earthquakes with magnitudes M>6 according to the Richter scale. Also, the local and regional seismic-geological characteristics of the region can be regarded as typical for the territory of the Republic of Macedonia. The network was installed in the period 1981-1985. Regarding the goals and the expected results, the eastern part of the City of Ohrid (Fig.2) was chosen as the most suitable location. The network consists of five individual sets of instruments (Fig. 3) that are connected to a standard time code receiver. Individual systems are located on bedrock (1), characteristic soil (3) and buildings (1) (Table 3).
In 2009, the instrument array was modernized, i.e., the network was upgraded by replacement of the old recording system by a real time monitoring system.
